DE2617060A1 - RECHLORINATED VINYL CHLORIDE POLYMERIZES - Google Patents

Description

The invention relates to a process for the dry chlorination of powdery vinyl chloride polymers, especially of vinyl chloride homopolymers, with gaseous chlorine.

Vinyl chloride polymers, including homopolymers of Vinyl chloride and copolymers of vinyl chloride with a maximum of 20 mol% one or more other monomers are understood, although they show numerous excellent properties, they also have a major disadvantage that they are at a relatively slightly higher temperature, between about 60 and 70 C, become unusable because they lose their dimensional stability. " This eliminates important areas of application, such as pipes or vessels for warm liquids.

It is known that vinyl chloride polymerizates by post-chlorination

can be made more heat resistant. The Vicat temperature, i.e. the

2 softening temperature of the polymer under a load of 5 kg / cm, as described in detail in the ISO-R 306 or ASTM-D 1525 standard, is generally used as a measure of the dimensional stability under heat.

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Post-chlorinated vinyl chloride polymers do not have a higher m <r Vicat temperature, they also have better fire retardant properties and are more resistant to chemicals than the original vinyl chloride polymers; they also have a low coefficient of linear expansion. On the other hand, post-chlorinated vinyl chloride polymers are more difficult to process and more brittle. By mixing with non-chlorinated ones Vinyl chloride polymers and / or with substances that improve flowability and impact resistance can have these disadvantages however, can be completely or largely remedied.

For the post-chlorination of vinyl chloride polymers, and especially of vinyl chloride homopolymers, are a number of processes in practice known. For example, polyvinyl chloride can be chlorinated in solution. Because of the poor solubility of vinyl chloride polymers, they are Chlorination at temperatures above 100 C, generally at 120 - 130 C, in inert solvents such as chlorobenzene or perchlorethylene. These processes are complex and do not provide a powdery product; she are therefore only used when the price is less critical, e.g. when processing re-chlorinated vinyl chloride polymers in paints, Adhesives, clothing preparations, etc.

For use in the construction industry, e.g. for hot water pipes, drainage pipes, Central heating pipes, colored window profiles and panel profiles, and in the process industry, e.g. for vessels and lines for storage and for Transport of hot or corrosive liquids, reactors for electrochemical Industry, etc., in the manufacture of such pipes, vessels, profiles, etc., one starts from powdered vinyl chloride polymers, especially from Polyvinyl chloride. When using post-chlorinated vinyl chloride polymers, it is with regard to stabilization and further processing according to the It is desirable that these polymers also be used in powder form in conventional processes To be available; for this purpose, post-chlorination processes are used in which - unlike post-chlorination in solution - the post-chlorinated vinyl chloride polymers in powder form.

For the production of post-chlorinated vinyl chlorides in powder form processes which work in aqueous suspension have become known, inter alia from Dutch patent application 66.11628, den British patents 948,372, 976,001 and 1,120,769, the German patent applications 1,811,472, 1,817,523 and 2,012,121 as well as from the French

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Patents 1,286,811, 1,309,937, 1,462,246 and 1,580,070.

Powdered polyvinyl chloride is suspended in water, then in the presence of a free radical initiator at an elevated temperature, chlorine is released the suspension is passed until the vinyl chloride polymer has the undesirable chlorine content has reached.

A disadvantage of this process is that chlorine increases when it is increased

Temperature dissolves poorly in water. The chlorination even takes place at

2 increased pressure only slowly. So is under a pressure of 4 kg / cm at a temperature rising from 35 to 85 C with lauryl peroxide or diisopropyl peroxydicarbonate as a radical initiator, a reaction time of 12 hours required to achieve the chlorine content, which is 56.8% by weight for normal polyvinyl chloride is to increase to 67.9 wt%.

The so-called gel phase processes are not compatible with the post-chlorination process associated disadvantage of the long reaction time adhering to the aqueous suspension. Vinyl chloride polymers and post-chlorinated vinyl chloride polymers are under 80 C insoluble in carbon tetrachloride and chloroform, but they swell in them to form gel-like products.

In the gel phase process, pulverulent vinyl chloride polymer is then suspended in one of these solvents and then passed through the suspension with stirring and in the presence of a free radical initiator, for example a peroxy compound, or free radical initiating radiation at 50-60 ° C. Such processes are described in German patent applications 1,942,902 and 2,064,171, in German patent specification 1,208,889 and in Italian patent specification 852,492. The vinyl chloride polymer particles swell strongly in carbon tetrachloride or chloroform. The diffusion of the chlorine and initiator molecules in these strongly swollen particles proceeds well. Chlorine is readily soluble in the dispersant; therefore, in the production of post-chlorinated polyvinyl chloride with a chlorine content of up to about 68% by weight, relatively high chlorination rates - of 2 to 2 hours - can be achieved.

As a result of the strong swelling, one can only use the rather dilute ones Use out suspensions with a maximum of about 20% by weight vinyl chloride polymer, as otherwise the suspensions can no longer be touched. A disadvantage of this method is that the swelling becomes greater as the chlorine content increases and that with a chlorine content of about 68% by weight, the Particle occurs, whereby stirring is almost impossible. From the viscous gel mass

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In this case, no more powdery product can be obtained during processing unless elaborate grinding is carried out.

At the beginning of the sixties a process was invented in which one works in the aqueous gel phase. From this in the American Patent 2,996,489 described method has one in large-scale Being able to develop a process that can be carried out on a scale.

In the post-chlorination in aqueous gel phase which is carried Chloi ^- ation system three-phase in a stirred, which consists of polymer particles, carbon tetrachloride, or chloroform and water. By adding water, a smaller amount of carbon tetrachloride or chloroform is sufficient, the system can be stirred more easily and still relatively high chlorination rates can be achieved. As a result of the disintegration of the polymer particles, it is also possible in this process to chlorinate up to a maximum chlorine content of about 68% by weight.

Finally, processes have also been described in which vinyl chloride polymers are stirred in a fluidized bed or in some mechanical way be chlorinated with gaseous chlorine, e.g. in the Dutch Patent applications 65.05868 and 66.00454, in the German patent applications 1,811,059, 1,932,589, 1,941,332 and 2,222,640 as well as in the German patents 1,110,873 and 1,259,573.

The chlorination is carried out at a temperature between 40 and 140 C in the presence of radical-initiating radiation or of a gaseous or initiator which forms solid radicals. These processes are generally not carried out isothermally. You start at moderately increased Temperature and gradually increases it, often up to values at which radical formation through thermal initiation also begins to play a role. Direct application of temperatures at which thermal initiation plays a role causes the decomposition of the as yet unreacted vinyl chloride polymer. The reproducible execution of an exothermic gas phase process in which the temperature varies under controlled conditions has to be, however, is extremely difficult. Such a process cannot be carried out continuously either. A must for a continuous process you either chlorinate at a single temperature, or the chlorination run in two or more stages. It has also been shown that a post-chlorination in the gas phase or in aqueous suspension

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chlorinated vinyl chloride polymer has a significantly lower Vicat temperature than a vinyl chloride polymer with deniselbon chlorine content after a gel phase process after chlorination. According to the American patent specification 2,996,489, the ratio of the 1,2-dichloroethane units to the 1,1-dichloroethane units that are formed during the post-chlorination should have an important influence on this. Later studies by Trautvetter (Kunststoffe Plastics 2 (1966) 54-58) have shown that this view is wrong. Today it is assumed that in the gas phase process an inhomogeneous chlorination of the vinyl chloride polymer particles causes the relatively low Vicat temperature. During chlorination in the gas phase, the vinyl chloride polymer particles are not swollen and, with the exception of the surface, are therefore difficult to access both for chlorine molecules and for initiator molecules. When using radical-initiating radiation, it does not penetrate or penetrates into the interior of the particles in a greatly weakened manner. Solid, powdery initiators cannot diffuse into the polymer particles. Chlorine radicals formed in the gas phase can only penetrate the particles when the outer layers are completely chlorinated. Only gaseous initiators could diffuse into the polymer particles and in this way remedy the disadvantages associated with the inhomogeneous chlorination. "The use of fluorine as a gaseous initiator is known from German patent application 2.222.640.

Attempts to use thermal radical initiation are unsuccessful remained. The thermal initiation only takes on a certain importance at temperatures of at least 75 C; adequate chlorination rates

ο ο

only reached at at least 100 C. At temperatures above about 80 C occurs however, thermal degradation of the vinyl chloride polymers. Therefore, gas phase processes are often completely below 80 C in the presence run of an initiator, or partially below 80 C with a radical-forming initiator or with radical-initiating radiation and partially at higher temperatures. Post-chlorinated polyvinyl chloride has a higher heat resistance than the polyvinyl chloride itself and apparently the temperature can be increased after a certain time has already been chlorinated without the risk of the polyvinyl chloride polymer is dismantled. A difficulty with this method is that it cannot be determined exactly when the temperature will increase can be without decomposition. The greatest disadvantage is still that the Vieat temperatures are significantly below those in the post-chlorination according to the words achieved by the GeIpi.ase method.

6 0 9 8 4 5 / Π 9 4 8

Surprisingly, it has now been found that the above The disadvantages of the gas phase process described are thereby eliminated can that one - and this characterizes the present invention - in the absence of radical-forming initiators and / or of the radical formation initiating radiation the powdery vinyl chloride polymer, namely the vinyl chloride honiopolymer, in a first stage at a Temperature from - 20 C to a slightly elevated temperature of at most 50 C in a chlorine atmosphere, then the temperature

in a second stage to a minimum of 70 C, but below the agglomeration temperature of the polymer, increased in such a way that thermal radical formation occurs, and that the chlorination is continued until the desired Chlorine content has been reached, the polymer being held in a chlorine atmosphere at a temperature of not more than 50 ° C. until at the subsequent chlorination at temperatures at which thermal radical formation occurs, no thermal degradation and no associated discoloration take place. With the aid of the process according to the invention, post-chlorinated vinyl chloride polymers can be produced Manufacture Kit Vicat Teniperatures that match those of the Gel phase process post-chlorinated vinyl chloride polymers with appropriate Chlorine content are to be compared. The post-chlorinated vinyl chlorine products according to the invention differ not only in terms of their properties, but above all from an economic point of view in a favorable sense of the previous ones according to the known gas phase process, post-chlorinated vinyl chloride polymers.

It is assumed, even if this is not binding for the applicant The explanation to be considered is that here a kind of stabilization of the vinyl chloride polymer by saturation of the previously unsaturated part thereof plays a role, whereby the chlorination at temperatures at which thermal radical formation occurs, can be carried out without the the aforementioned thermal degradation of the Vinylchloridpolyip.erisate occurs. At a Such thermal degradation also changes the color of the polymer. With the aid of the process according to the invention, pure white powders are obtained.

Molecular chlorine adds, even at low temperatures, according to an ionic mechanism to a double bond. Vinyl chloride polymers are iirmor somewhat unsaturated. In the presence of chlorine radicals takes place mainly substitution in the allylic position compared to the unsaturated one Bonding takes place while little or no addition to the unsaturated bond occurs. In order to favor the ionic addition reaction, the formation of

- V ~~

therefore suppressed by chlorine radicals in the so-called stabilization period or at least not been suggested. It must therefore not be a radikr.l-forming Initiator be present or no radical-initiating irradiation takes place; also, the temperature should be chosen so that no or as much as possible little thermal radical formation occurs.

Because the addition of chlorine to a double bond even at temperatures under O C runs very quickly, the stabilization meant here can be carried out at any temperature at which no or hardly any radical formation occurs, i.e. at temperatures of at most 50 and preferably at most 35 C. Under atmospheric pressure, chlorine becomes liquid at - 34 C, under a pressure of 8 ata at about 26 C. Temperatures are too high for stabilization choose that are above the dew point of chlorine; these are under atmospheric Pressure generally be at least -20 ° C. Though the addition runs rapidly even at low temperatures, the curve is here intended stabilization is determined by the diffusion velocities. So that these are not unnecessarily slowed down without there being any demonstrable advantages, the temperature is preferably chosen not below 0 ° C. and the treatment with chlorine in the first stage is preferably carried out at temperatures at about 20 - 35 C, i.e. the ambient temperature in closed rooms. When installed outdoors, the temperatures can be high be apart; Among other things, it can be with regard to reproducibility It may be advantageous to heat or cool a little so that the stabilization takes place at temperatures of 20 - 25 C. It has shown, that the stabilization is associated with a slight exothermic effect. The temperature rise is generally at most 10 C; also from For this reason, an initial temperature of 20-25 ° C is preferable.

Vinyl chloride polymers such as these according to technical known per se Processes obtained by means of suspension, emulsion or bulk polymerization have a certain porosity. Both with the stabilization referred to here As with the chlorination itself, the chlorine has to pass through the pores into the interior of the polymer particles but also into the solid itself diffuse. The time required for this stabilization is different from the Porosity and particle size depend on and can be easily determined by first making the vinyl chloride polynierisat different

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26170R0

long at ambient temperature or slightly elevated temperature in one Let the chlorine atmosphere linger and then preferably with one Temperatures above 100 C, especially between 110 and 130 C chlorinated. If the stabilization time was too short, the

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Chlorination at temperatures above 100 C results in more or less discolored products. The stabilization time should therefore be chosen long enough so that fine, white, non-discolored powders are obtained after chlorination at high temperatures. The stabilization should last at least 30 minutes and preferably a stabilization time of at least 45 minutes will be used. A longer stabilization time is not harmful in any way, but for economic reasons it will not be chosen longer than necessary.

The stabilization meant here should take place at temperatures in which no thermal degradation of Viriylchloridpolymerisaten occurs and the formation of chlorine radicals is still negligible, i.e. at temperatures of at most 50 C and preferably at most 35 C. Radiation initiating radicals, i.e. radiation with a wavelength of less than 4800 A, or free radical initiators must not be present be. In the stabilization period, the vinyl chloride polymer particles become saturated with chlorine molecules.

Then .wird the vinyl chloride polymer in the chlorine atmosphere heated to reaction temperature. The heating time is not important to the course of the process, but is preferred for practical reasons kept short.

The chlorination itself is then carried out at an almost constant temperature. The chlorination temperature is high enough choose so that the chlorination of the vinyl chloride polymer via a thermal Radical initiation proceeds at a reasonable rate. the

ο The chlorination temperature is therefore preferably not chosen below 100 C.

On the other hand, the temperature should not be selected so high that the Agglomerated vinyl chloride polymer; the temperature will therefore be a maximum of 140.degree. C., preferably a maximum of 130.degree.

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The chlorination can take place both under atmospheric conditions, to some extent reduced or increased pressure. A certain.ussen Reduced pressure has the advantage that if there is a leak in the chlorination plant or the supply or discharge lines, no chxor is released into the atmosphere got. On the other hand, air can penetrate the system in the event of a leak; the presence of even small amounts of oxygen has an unfavorable effect on the The course of the chlorination reaction. The chlorination is generally

2
carried out at a pressure of at least 0.8 kg / cm.

In the case of chlorination under increased pressure, the associated higher chlorine concentration increases the diffusion into the pores and particles proceed faster, thereby accelerating the chlorination as a whole.

2 For practical reasons, the pressure is not selected above 10 kg / cm.

2
Apparatus suitable for pressures above 10 kg / cm is essential

2 more expensive than equipment that works at pressures of up to 10 kg / cm can be. Such disadvantages are not offset by corresponding advantages. The stabilization is related to the condensation point

2
run by chlorine at a pressure of up to 8 kg / cm. The chlorination is an exothermic process and should not proceed so quickly that the local temperatures are so high that the vinyl chloride polymer agglomerates and / or discolors. Good heat dissipation must be ensured, which is achieved by chlorinating the vinyl chloride polymer in the fluidized bed process, or for good mixing and good dissipation of the heat through the wall and / or via coolants installed in the reactor. A disadvantage is that relatively large amounts of gas are required for the chlorination of vinyl chloride polymer in the fluidized bed, although this gas can be fed back. Thorough mechanical mixing is preferably used, which, if desired, can be combined with a gas flow which is per se less than is necessary for chlorination in the fluidized bed process. It is possible to chlorinate in a pure chlorine atmosphere, but if desired, the chlorine can also be diluted with a gas which is inert to the vinyl chloride polymer, which can be advantageous in the chlorination of vinyl chloride polymer according to the fluidized bed system.

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The present process can be used for vinyl chloride polymers use with a maximum of 20% by weight of one or more other monomers. Compounds which are copolymerizable with vinyl chloride are about Vinylidene chloride, vinyl esters, such as vinyl acetate, vinyl butyrate and vinyl benzoate, Acrylic acid and methacrylic acid, alkyl esters, their amides or nitriles, such as ethacrylic acid, ethyl acrylate, methyl methacrylate, butyl methacrylate, Acrylamide and acrylonitrile, vinyl aromatic compounds, such as Styrene, chlorostyrene, methyl styrene, xthy! Styrene, vinyl naphthalene, alkyl esters of maleic acid and fumaric acid, e.g. diethyl maleate, vinyl alkyl ethers and vinyl alkyl ketones, vinyl pyridines, copolymerizable olefins such as ethylene, Propylene, butylene, isobutylene, 4-methylpentene-1. Mixtures of Find polyvinyl chloride with copolymers of vinyl chloride application. Copolymers here are both random copolymers such as Graft and block polymers understood. As graft polymers v / ground at this point especially the graft polymers of vinyl chloride on copolymers of ethylene and vinyl acetate or ethylene and alkyl acrylates. the Post-chlorination of graft polymers of vinyl chloride on copolymers of ethylene and vinyl acetate is per se from the British patent 1,095,831 known. However, the present process is preferably used for chlorinating homopolymers of vinyl chloride.

The method according to the invention can be applied to polyvinyl chloride with widely differing molecular weights. The polyvinyl chlorides normally used in TechP.iek have a K value that is generally between 45 and 80 and mostly between 50 and 75. Fikentscher (Zellulosechemie J ₁ ^ (1932) 58) defined the K value, a measure of the molecular weight.

The chlorination can continue until the chlorination is maximal, i.e. up to a chlorine content of 73.2% by weight, corresponding to 2 chlorine atoms 2 carbon atoms each. Less extensive chlorination, up to one Chlorine content of around 65-70% by weight, however, is acceptable.

Of course, you can also chlorinate down to a lower chlorine content. There are e.g. applications of post-chlorinated polyvinyl chloride with about 60 wt .-% Known chlorine. Such post-chlorinated polyvinyl chlorides can also be used are advantageously produced with the aid of the process according to the invention.

609845/0948

The ... with the aid of the method according to the invention produced post-chlorinated Vinyl chloride polymers, especially those with a high chlorine content, are brittle and difficult to process; the brittleness and However, processability can be increased by mixing with normal polyvinyl chloride uud / or with the flowability and / or the impact strength Funds are significantly improved. True, the Vicat temperature takes through Mixing with other products generally decreases, but the final value is generally above the Vicat temperature of the non-post-chlorinated Polyvinyl chloride. The mixtures obtained in this way are therefore very suitable for applications in which a higher Vicat temperature is desired e.g. for hot water pipes, central heating pipes, colored profiles, which can be exposed to sunlight, vessels in which hot and / or corrosive substances are stored or processed, etc.

The post-chlorinated vinyl chloride polymers do not have just one better mechanical strength at elevated temperature; at elevated temperature they are also better against decomposition and generally against the influence resistant to chemicals.

The properties of those post-chlorinated by the process according to the invention Vinyl chloride polymers agree to a large extent with the properties of the post-chlorinated polymers produced with the aid of the gel phase process Vinyl chloride polymers, as described, for example, in the American patent 2,996,489 is described, and thus differ in favorable In the sense of the post-chlorinated according to the previously known gas phase process Vinyl chloride polymers; differs from the known gel phase process the method according to the invention is particularly advantageous from an economic point of view cheap.

As already mentioned above, the post-chlorinated vinyl chloride polymers are They are generally more brittle and more difficult to process than the original vinyl chloride polymers. The higher the chlorine content, the more brittle and difficult to process the product. Even if that with non-post-chlorinated If vinyl chloride polymer is mixed and processing aids known per se are used, it is nevertheless often desired. be, to process the mixtures obtained in this way at a higher temperature than the normal vinyl chloride polymers. It is mostly then It is desirable to add a stabilizing agent to avoid decomposition when the individual components are mixed in.

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• .ΙΟ -

The vinyl chloride polymer used for post-chlorination is in powder form. The particle size should generally be on average above 10 U and preferably most of the particles are larger than about 50/1. Coarser vinyl chloride polymers with particle sizes of up to 0.5 mm can be used very well.

The starting polymer should be somewhat porous.

According to the generally known suspension, emulsion or bulk polymerization The vinyl chlorides produced are all more or less porous. porosity and particle size are co-determining the time required to Stabilization of the vinyl chloride polymer, which is allowed to stay in a chlorine atmosphere at the most slightly elevated temperature, and also affect the rate of chlorination at elevated temperature. Vinyl chloride polymers with a porosity of about 0.05 to about 0.5 cm / g Pore volumes are therefore strongly preferred.

There is no difference between the particle size and the stabilization rate clear relationship. Polyvinyl chloride consists of agglomerates of very small so-called primary particles. The particle size, such as this e.g. by means of Sieve analysis is determined, concerns the size of the agglomerates. In the stabilization period the chlorine can penetrate into the agglomerates and then diffuse into the Uussorst small primary particles. It turns out that the required Stabilization time only slightly dependent on the size of the agglomerates is.

The chlorination according to the invention is carried out in the absence of oxygen to execute. Technical chlorine contains carbon monoxide, carbon dioxide, nitrogen and traces of oxygen. Chlorine with an oxygen content of up to 60 ppm can be used well, larger amounts of oxygen have a noticeably unfavorable effect affect the quality of the post-chlorinated products and are therefore considered inadmissible considered. Technical chlorine also contains small amounts of iron compounds, which can accelerate the chlorination of vinyl chloride polymers in the gas phase to a greater or lesser extent. The iron compounds can die Adversely affect the reproducibility of the process and are therefore preferably removed from the chlorine gas by doing this, for example, with water or better to wash with an acid such as hydrochloric acid or concentrated sulfuric acid. Washing with concentrated sulfuric acid is preferred because of the chlorine gas then stays dry. You can also dilute the chlorine with an inert gas such as nitrogen or hydrogen chloride and use a chlorine atmosphere, which contains 30-100% by volume of chlorine. Thinning can sometimes be beneficial

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be connected when holding the vinyl chloride polymer in the fluidized state; relatively large amounts of gas are required for this. Applying undiluted In general, however, chlorine is preferable.

The post-chlorination of vinyl chloride polymers produces hydrogen chloride free. After the chlorination has ended, the polymer still contains chlorine and hydrogen chloride, both of which are powerful substances Nitrogen saturation at elevated temperature from the post-chlorinated polymer can be removed. If necessary, one can after the nitrogen wash possibly still existing chlorine and hydrogen chloride sperm and harmful by first treating the chlorinated polymer with methanol, which reacts with the chlorine to formaldehyde and hydrogen chloride, and then Washes with a sodium bicarbonate solution or another alkaline solution to bind the hydrogen chloride.

The invention is further illustrated by the following examples, without this in any way restricting the invention.

The experiments described in the examples are carried out in one of the Figure executed device shown schematically. In this figure is:

1. a gas bottle with chlorine at the same temperature as the surrounding area (about 22 C);

2. a gas flow meter;

3. a gas washing bottle with concentrated sulfuric acid;

4. Non-return vessels;

5. a rotating drum;

6. a gas wash bottle with a solution of sodium hydroxide in water;

7. a thermocouple (chrome-alumel) connected to a recorder; and

8. a thermostatically controlled oil bath heater.

The rotating glass drum has a wall thickness of 2-3 mm, a length of about 15 cm and an inside diameter of about 15 cm. The speed of rotation is about 60 rpm. The drum is filled with 100-150 g of polyvinyl chloride powder filled. Before the chlorination, the apparatus is first flushed with nitrogen in order to expel the air, especially the oxygen in it. Afterward a continuous stream of chlorine gas with a temperature of about 22 C and a throughput of 44.25.10 kg of chlorine each is generated under atmospheric pressure Second set per kg of polyvinyl chloride. The stabilization time, i.e. the time that the polycinyl chloride dies at a temperature of at most 50 C. was the ambient temperature during the experiments - lingered in a chlorine atmosphere, is 1 hour. The temperature rises to some extent, but remains but below 35 ° C. When filled with 150 g of polyvinyl chloride, the highest measured temperature rise is about 10 C.

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After the stabilization period, the drum and its contents, with the help of the oil bath, in which the drum rotates, to the desired reaction temperature T erT "'tzt.

In order to maintain the desired roaktioristeniperatur during the reaction, must the temperature of the oil bath must be kept at about T + 5 ° C.

After the desired reaction time has elapsed, the supply of chlorine is ended; then with the help of a vigorous stream of nitrogen, chlorine and Hydrogen chloride from the apparatus and as much as possible from the post-chlorinated Product expelled. The post-chlorinated product is then taken up in methanol, that with the remaining unbound chlorine reacts to formaldehyde and hydrogen chloride. After filtering off, the post-chlorinated Polyvinyl chloride then with a dilute solution of sodium carbonate in water / water (50 g NaHCO / 1), with water and finally with

Washed methanol, whereupon it is dried at 40 C in a vacuum kiln, until a constant weight is achieved.

Dor the chlorine content of the products manufactured in this way both by means of element analysis and by determining the increase in weight of the polyvinyl chloride used. The latter method generally gives the most accurate results (up to 0.10%).

Example I.

A series of tests is carried out with the Varlan 5900, Varlan 6600 and Varlan 7100. These are polyvinyl chlorides produced by the DSM company by means of suspension polymerization. Of these 3 types of polyvinyl chloride, the K value of which is 59.66 and 71, respectively, the particle size distribution is determined by means of sieve analysis and the average is determined on the basis of this
Particle size (d) calculated. In addition, the fill weight that

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Porosity and the BET surface area are determined. The values found are stored in Table 1 reproduced.

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Table 1

Varlan-5900

Varlan-6600

Varlan -7100

Sieve fraction content sieve fraction content " ¹ tion (μ)% tion (μ)%

Sieve fraction content (μ)%

63

88

125

177

250

1.5

8.0

37.5

91.2

99.7

63

88

125

177

250

1.0

7.8

31.6

83.1

99.6

63

88

125

177

250

d ₅₀ (μ) 138

Fill weight V (g / cm) 0.590

Porosity (cm / g) 0.09

BET surface area (m / g) 0.1

145 0.520 0.21 0.8

130

0.490

0.27

1.1

These 3 types of polyvinyl chloride are produced with the aid of the method according to the invention chlorinated; to do this, they must first have 1 hour at ambient temperature in one Linger in the chlorine atmosphere and then at 125 C for 20 minutes Post-chlorinated for up to 4 hours. The results are shown in Table 2. The response times are total times, i.e. including the 60-minute stabilization.

Table 2 Weight% Varlan-6600 Wt% Varlan-7100 Wt% Cl Reaction Cl Reaction Cl Varlan-5900 Time Time Reaction 56.8 Min. 56.8 'Min. 56.8 Time 57.1 0 57.1 0 58.0 Min. 59.6 60 61.8 60 63.0 0 61.3 80 63.7 80 64.8 60 62.9 90 65.1 - 90 66.2 80 65.0 100 66.8 100 67.5 90 66.9 120 68.4 120 69.2 100 67.4 150 68.7 150 70.1 120 67.8 180 69.6 180 72.0 180 240 70.2 300 240 300 300

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Example ^? -

Varlan 6600 is chlorinated in the manner described in Example 1. The Vicat tempatures of the chlorinated products are measured. The results can be found in Table 3.

Table 3

Wt% Cl Vicat temperature
( ⁰ C) reaction time
(Min.) 56.8 85 0 57.4 87 60 62.7 107 80 64.6 114 100 66.4 124 120 67.6 135 150 67.8 134 180 69.0 146 240 70.0 151 300 Example 3

For comparison with the products obtained in Example 2, Varlan 6600 ge mils s chlorinated in a gel phase process. For this purpose a with an agitator provided container is used, in which 500 g Varlan 6600 and 3 1 (4.8 kg) Carbon tetrachloride are introduced. The suspension is stirred and at ambient temperature, i.e. at about 25 C, there is 0.5% by weight of diisopropyl peroxydicarbonate added, calculated on the polyvinyl chloride. The temperature of the suspension is then gradually increased to 50 C when performing of gaseous chlorine through the suspension. The heating time is about 15 minutes. The results are shown in Table 4. The response times include the heating time.

Table 4 Wt% Cl Vicat temperature
(° C) 58.9 89 reaction time
Min. 62.0 101 45 64.9
68.3 6098
143 60 69.2 148 75
105 120

The same series of experiments is carried out again, this m; -l as free radical initiator 0.5 wt .-% azobisisobutyronitrile are present: the The temperature of the suspension is brought to 70.degree. The results can be found in table 5.

Table 5

Reaction time wt .-% Cl Vicat temperature

Min. (° C)

45 65.0 119

60 66.8 138

90 70.5 149

Example 4

For comparison purposes, reference is made to the in a series of experiments described in the introduction to the examples executed in the sense that Varlan 6600 without this initially at Ambient temperature or slightly elevated temperature with a chlorine atmosphere is brought into contact, is heated immediately to 75 C within about 10 minutes, with 0.5% by weight as the radical-forming initiator Azobisisobutyronitrile are added, calculated on the polyvinyl chloride. The results are shown in Table 6.

Table 6 Weight? Ό Cl Vicat temperature
( ⁰ C) 62.0 92 reaction time
Min. 62.8 99 60 64.5 104 90 66.2 100 180 300

These examples show that in the case of chlorination in the gas phase with a Free radical initiator post-chlorinated products are obtained without a previous stabilization period, the Vicat temperature of which is significantly lower than that of the post-chlorinated products manufactured using the gel phase process or the products post-chlorinated according to the present invention with a corresponding chlorine content.

6 0 9.8 4 5/0 9 k 8

Example 5

Varlan 6600 is made according to the procedure described in Example 1 chlorinated at different temperatures. The results are shown in Table 7.

Table 7 125 ⁰ C Reaction temp. 100 ° C Reaction temp. 75 ° C Wt% Cl Reaction Wt% Cl Reaction Wt% Cl Reaction temp. Time Time Reaction Min. Min. Time 0.568 0 56.8 0 56.8 Min. 0.571 60 57.1 60 57.1 O 0.618 80 60.9 80 58.3 60 0.637 90 62.0 90 58.8 80 0.651 100 62.6 100 59.8 90 0.668 120 64.5 120 60.4 100 0.684 150 66.0 150 61.8 120 0.687 180 66.4 180 62.8 150 0.697 240 67.4 240 63.8 180 0.702 300 68.2 300 65.0 240 300 Example 6

In a series of experiments, the influence of the chlorine concentration checked for the rate of chlorination. In the manner described in Example 1, the chlorination with a Chlorstroir. under atmospheric pressure with a temperature of about 22 ° C and a throughput of 44.25.10 kg Cl per second per kg of the polyvinyl chloride introduced into the vessel. In order to obtain different concentrations of chlorine, this constant chlorine is used stream mixed with a stream of nitrogen. The nitrogen flow is chosen so that a chlorine concentration of 66% by volume or 34% by volume is achieved. The results of these tests carried out under atmospheric pressure, in which the chlorination takes place at 125 C are shown in Table 8.

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Table 8 % By volume Cl ₀ C = 66 vol. -% egg ^c ci ^{= 34 Vo1} % Ci ₂ Wt. ~% Cl Reaction Wt% Cl Reaction Wt% Cl C = 100 Time Time Reaction (Min.) (Min.) Time 56.8 0 56.8 0 56.8 (Min.). 57.1 60 57.1 60 57.1 0 61.8 80 60.5 80 59.6 60 63.7 90 61.4 90 60.0 80 65.1 100 63.0 100 60.9 90 66.8 120 64.6 120 62.5 100 120

Although the transferred absolute amount of chlorine is the same in all cases, shows that the chlorination by dilution with an inert gas is slower runs. It can be calculated that log. In this case, K η corresponds to 0.74.

ο = η log C C

+ C;

Example 7

The minimum time that the polymer has to warp in the chlorine atmosphere in the first stage can be determined in a simple manner using a few Determine experiments. For the Varlan 6600, this time is determined for stabilization under atmospheric pressure at 25 C. This is done according to the above Method Varlan 6600 brought into contact with chlorine under atmospheric pressure at 25 C in the rotating drum, after a time lapse heated from 0 to 120 minutes to 130 ° C and chlorinated at this temperature for 2 hours. 0 minutes on the first attempt means that the heating

tion to 130 C begins at the same time as the chlorine is passed through. The results are listed in Table 9.

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Table 9

Stabilization time
at 25 ° C
(Min.)

Response time at 130 ° C (min.)

Appearance of the
End product

Wt% Cl

120 120 120 120 120 120

^ strong to less strong
Discoloration

fine, white powder fine, white powder fine, white powder

69.7 69.6 69.7

The table shows that with the Varlan 6600 among those described here Reaction conditions a time of 45 minutes for the first reaction stage sufficient.

fs () 9 HA h / 11 Μ / ♦ R

Claims (1)

PATENT CLAIMS 1
} · '. Process for the dry chlorination of pulverulent vinyl chloride polymers with gaseous chlorine, characterized in that in the absence of radical-forming initiators and / or of radiation initiating radical formation, a pulverulent vinyl chloride polymer in a first stage at a temperature of -20 C up to a slightly higher temperature of at most 50 ° C in a chlorine atmosphere, the temperature is then increased in a second stage to a minimum of 70 C, but below the agglomeration temperature of the polymer, in such a way that thermal radical formation occurs, and that generally chlorinated until the desired chlorine content is reached is, the time that the polymer remains in the first stage at a temperature of a maximum of 50 C in a chlorine atmosphere, is chosen at least long enough that in the second stage at temperatures at which thermal radical formation occurs, no thermal degradation and none in order to associated discoloration take place. 2. Process for the dry chlorination of pulverulent vinyl chloride polymers with gaseous chlorine, characterized in that in the absence of radical-forming initiators and / or radiation initiating radical formation, the pulverulent vinyl chloride polymer in a first stage ο
a temperature of -20 C up to a slightly higher temperature of a maximum of 50 C for at least 30 minutes in a chlorine atmosphere, then in a second stage the temperature is increased to at least 70 C, but below the agglomeration temperature, in such a way that thermal Radical formation occurs, and that one chlorination up to the desired chlorine content. 3. The method according to any one of claims 1-2, characterized in that the Treatment with chlorine in the first stage at a temperature of at least 0 ° C.
4. The method according to any one of claims 1-3, characterized in that the treatment with chlorine in the first stage at a temperature of a maximum of 35 C is carried out. 5. Vez-drive according to one of claims 1-4, characterized in that the treatment
begins. ο Treatment with chlorine in the first stage at a temperature of 20-25 C 60984 5/0948 G. Procedure according to a; of claims 1-5, characterized in that the Vinyl chloride polymer in the first stage at least 30 minutes in the Let the chlorine atmosphere evaporate.
7. The method according to any one of claims 1-6, characterized in that the vinyl chloride polymer in the first stage at least 45 minutes in the Chloratir.osphere lets linger,
β. Process according to one of Claims 1-7, characterized in that the chlorination in the second stage is carried out at a temperature of at least 100 ° C executes.
9. The method according to any one of claims 1-8, characterized in that the chlorination is carried out in the second stage at a temperature of at most 140C. 10. The method according to any one of claims 1-9, characterized in that the Performs chlorination in the second stage at a temperature of 110-130 C. 11. The method according to any one of claims 1-10, characterized in that in 2 of the first and / or in the second stage a pressure of at least 0.8 kg / cm applies. 12. The method according to any one of claims 1, -11, characterized in that in the first stage works under a chlorine pressure of maximum 8 kg / cm. 13. The method according to any one of claims 1-12, characterized in that the 2 Chlorination in the second stage under a pressure of no more than 10 kg / cm executes. 14. The method according to any one of claims 1-13, characterized in that one Chlorine-containing atmosphere is used, which contains 30-100% by volume of chlorine. 15. The method according to any one of claims 1-14, characterized in that one Vinyl chloride polymer with a K value of 45-80 is used. IG. The method according to claim 15, characterized in that one Vinyl chloride homopolymer used.
17. The method according to any one of claims 15-16, characterized in that a vinyl chloride polymer prepared by means of suspension polymerization is used. 60984 5/0948